Apex Developer Guide

Getting Started
Writing Apex
Ways to Invoke Apex
Finishing Touches
Reference
Apex DML Operations
ApexPages Namespace
AppLauncher Namespace
Approval Namespace
Auth Namespace
Cache Namespace
Canvas Namespace
ApplicationContext Interface
CanvasLifecycleHandler Interface
ContextTypeEnum Enum
EnvironmentContext Interface
RenderContext Interface
Test Class
Canvas Exceptions
ChatterAnswers Namespace
ConnectApi Namespace
Database Namespace
Datacloud Namespace
DataSource Namespace
Dom Namespace
Flow Namespace
KbManagement Namespace
Messaging Namespace
Process Namespace
QuickAction Namespace
Reports Namespace
Schema Namespace
Search Namespace
Site Namespace
Support Namespace
System Namespace
TerritoryMgmt Namespace
TxnSecurity Namespace
UserProvisioning Namespace
Appendices
Glossary
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Canvas Exceptions

The Canvas namespace contains exception classes.

All exception classes support built-in methods for returning the error message and exception type. See Exception Class and Built-In Exceptions.

The Canvas namespace contains this exception:

Exception Description
Canvas.CanvasRenderException Use this class in your implementation of Canvas.CanvasLifecycleHandler.onRender(renderContext). To show an error to the user in your onRender() implementation, throw a Canvas.CanvasRenderException, and the canvas framework will render the error message to the user.  This exception will be managed only within the onRender() method.

Example

The following example implementation of onRender() catches a CanvasException that was thrown because a canvas URL was set with a string that exceeded the maximum length. A CanvasRenderException is created and thrown to display the error to the user.
See the Force.com Canvas Developer’s Guide for additional examples that use CanvasRenderException.